Digital video broadcasting (DVB)

The standard consists of four parts each covering a different structure of the transmitter network: covers sheer terrestrial transmission with single and multi-aerial structures that require only a single aerial and tuner on the receiver side; covers sheer terrestrial transmission with multi-aerial structures on both ends. Terminals suitable for this profile need to employ two tuners as well...

Digital Video Broadcasting (DVB);

Next Generation broadcasting system to Handheld,

physical layer specification (DVB-NGH)

DVB Document A160

November 2012

Contents

Intellectual Property Rights 10

Foreword 10

1 Scope 11

2 References 11

2.1 Normative references 12

2.2 Informative references 12

3 Definitions, symbols and abbreviations 12

3.1 Definitions 12

3.2 Symbols 16

3.3 Abbreviations 22

Part I: Base profile 25

4 System overview and architecture 26

4.1 Input processing 27

4.1.1 Mapping of input streams onto PLPs 28

4.1.2 Encapsulation into baseband frames 28

4.2 Bit-interleaved coding and modulation, MISO precoding 29

4.2.1 FEC encoding and interleaving inside a FEC block 29

4.2.2 Modulation and component interleaving 29

4.2.3 Formation of interleaving frames for each PLP 29

4.2.4 Time interleaving (inter-frame convolutional interleaving plus intra-frame block interleaving) 29

4.3 Frame building, frequency interleaving 30

4.3.1 Formation of logical frames 30

4.3.2 Mapping of logical frames onto NGH frames 31

4.3.3 Logical channel types 33

4.3.4 Single tuner reception for frequency hopping 33

4.4 OFDM generation 34

5 Input processing 35

5.1 Mode adaptation 35

5.1.1 Input formats 35

5.1.1.1 Transport Stream packet header compression 36

5.1.2 Input interface 38

5.1.3 Input Stream Synchronization (optional) 39

5.1.4 Compensating delay 39

5.1.5 Null Packet Deletion (optional, for TS only, ISSY-LF, ISSY-BBF and ISSY-UP modes) 39

5.1.6 Baseband frame header (BBFHDR) insertion 40

5.1.7 Mode adaptation sub-system output stream formats 41

5.1.7.1 ISSY-LF mode, TS, GSE and GCS 42

5.1.7.2 ISSY-UP mode, TS and GSE 43

5.2 Stream adaptation 43

5.2.1 Scheduler 44

5.2.2 Padding 44

5.2.3 Use of the padding field for in-band signalling 44

5.2.3.1 In-band type A 45

5.2.3.2 In-band type B 49

5.2.4 Baseband frame scrambling 49

6 Bit-interleaved coding and modulation 50

6.1 FEC encoding 50

6.1.1 Outer encoding (BCH) 51

6.1.2 Inner encoding (LDPC) 52

6.1.3 Bit Interleaver 53

6.2 Mapping bits onto constellations 55

6.2.1 Bit to cell word de-multiplexer 55

6.2.2 Cell word mapping into I/Q constellations 60

6.3 Cell interleaver 63

6.4 Constellation rotation 65

6.5 I/Q component interleaver 67

6.6 Time interleaver 69

6.6.1 Division of interleaving frames into time interleaving blocks 70

6.6.2 Writing of each TI-block into the time interleaver 71

6.6.3 Mapping of interleaving frames onto one or more logical frames 73

6.6.4 Number of cells available in the time interleaver 76

6.6.5 PLPs for which time interleaving is not used 77

7 Distributed and cross-polar MISO 77

7.1 System overview 77

7.2 Transmit/receive system compatibility 77

7.3 MISO precoding 77

7.4 Block diagram 78

7.5 eSFN processing for MISO 78

7.6 Power imbalance 79

7.7 SISO/MISO options for P1, aP1 and P2 symbols 79

8 Generation, coding and modulation of layer 1 signalling 80

8.1 Introduction 80

8.1 L1 signalling data 81

8.1.1 P1 signalling data 81

8.1.2 L1-PRE signalling data 84

8.1.2.1 N-periodic spreading of L1-PRE data 95

8.1.3 L1-POST signalling data 95

8.1.3.1 L1-POST configurable signalling data 96

8.1.3.2 Self-decodable partitioning of the PLP loop in L1-POST configurable 106

8.1.3.3 L1-POST dynamic signalling 109

8.1.3.4 Repetition of L1-POST dynamic data 111

8.1.3.5 Additional parity of L1-POST dynamic data 112

8.1.3.6 L1-POST extension field 112

8.1.3.7 CRC for the L1-POST signalling 113

8.1.3.8 L1 padding 113

8.2 Modulation and error correction coding of the L1 data 114

8.2.1 Overview 114

8.2.1.1 Error correction coding and modulation of the L1-PRE signalling 114

8.2.1.2 Error correction coding and modulation of the L1-POST signalling 114

8.2.2 Scrambling and FEC encoding 117

8.2.2.1 Scrambling of L1-PRE and L1-POST information bits 117

8.2.2.2 Zero padding of BCH information bits 118

8.2.2.3 BCH encoding 120

8.2.2.4 LDPC encoding 120

8.2.2.4.1 LDPC encoding for L1-PRE 121

8.2.2.4.2 LDPC encoding for L1-POST 122

8.2.2.5 Puncturing of LDPC parity bits 123

8.2.2.5.1 Puncturing of LDPC parity bits for L1-PRE 123

8.2.2.5.2 Puncturing of LDPC parity bits for L1-POST 124

8.2.2.6 Generation of Additional Parity for L1-POST signalling 126

8.2.2.7 Removal of zero padding bits 127

8.2.2.8 Bit interleaving for L1-POST signalling 127

8.2.3 Mapping bits onto constellations 128

8.2.3.1 Mapping of L1-PRE signalling 128

8.2.3.2 Demultiplexing of L1-POST signalling 129

8.2.3.3 Mapping into I/Q constellations 130

9 Frames 130

9.1 Frame builder 130

9.2 Logical frame structure 131

9.2.1 Signalling of the logical frame 131

9.2.2 Mapping the PLPs onto logical frames 132

9.2.2.1 Allocating the cells at the output of the time interleaver for a given PLP 132

9.2.2.2 Allocating the cells of the PLPs 133

9.2.2.2.1 Allocating the cells of the Common and Type 1 PLPs 133

9.2.2.2.2 Allocating the cells of type 2 PLPs 134

9.2.2.2.3 Allocation of cells positions in the logical frame for each of the type 2 PLPs 134

9.2.2.2.4 Mapping of the time interleaver output cells for each type 2 PLP, together with any padding, to the allocated cell positions in the logical frame 137

9.2.2.2.5 Allocating the cells of type 3 PLPs 138

9.2.2.2.6 Allocating the cells of type 4 PLPs 138

9.2.3 Auxiliary stream insertion 138

9.2.4 Dummy cell insertion 139

9.3 Logical super-frame structure 139

9.4 Logical channel structure 140

9.4.1 Logical channel type A 140

9.4.2 Logical channel type B 141

9.4.3 Logical channel type C 141

9.4.4 Logical channel type D 141

9.4.5 Logical channel group 142

9.5 Mapping of logical channels to NGH frames 142

9.5.1 Mapping for logical channels type A 143

9.5.2 Mapping for logical channels type B 143

9.5.3 Mapping for logical channels type C 143

9.5.4 Mapping for logical channels type D 143

9.5.5 Restrictions on frame structure to allow tuner switching time for Logical Channels of Type C and D 143

9.6 Physical frames 145

9.7 Frame structure 145

9.8 Super-frame 145

9.9 NGH frame 147

9.9.1 Duration of the NGH-Frame 147

9.9.2 Capacity and structure of the NGH-frame 148

9.9.3 Mapping of L1-PRE signalling information to P2 symbol(s) 150

9.9.3.1 Addressing of OFDM cells 152

9.9.4 Dummy cell insertion 153

9.9.5 Insertion of unmodulated cells in the frame closing symbol 153

9.10 Future Extension Frames (FEF) 153

9.11 Frequency interleaver 155

10 Local service insertion 161

10.1 Orthogonal local service insertion (O-LSI) 161

10.1.1 Overview 161

10.1.2 O-LSI symbols and data cells 161

10.1.2.1 Overview 161

10.1.2.2 Power level of the O-LSI data cells 162

10.1.2.3 Filling of O-LSI symbols with LF data cells 162

10.1.3 O-LSI scattered pilot patterns 162

10.1.3.1 Location of O-LSI scattered pilot patterns 162

10.1.3.2 Power level of scattered pilot cells 163

10.1.3.3 Modulation of scattered pilot cells 163

10.1.4 O-LSI continual pilots 163

10.1.4.1 Overview 163

10.1.4.2 Location of O-LSI CPs 163

10.1.4.3 Power level of CP cells 163

10.1.4.4 Modulation of continual pilot cells 164

10.1.5 Normalisation factor K 164

10.2 Hierarchical local service insertion (H-LSI) 164

10.2.1 Overview 164

10.2.2 L1 signalling for hierarchical local service 165

10.2.3 LS burst header encoding 166

10.2.3.1 LS burst header coding 167

10.2.3.2 Cyclic delay 168

10.2.3.3 Scrambling of the lower branch 168

10.2.4 Frequency interleaving of local service cells 169

10.2.5 Insertion of local service pilots 169

10.2.5.1 Location of local service pilot cells 169

10.2.5.2 Amplitude of local service pilot 170

10.2.6 Hierarchical modulator 170

11 OFDM generation 173

11.1 Pilot insertion 173

11.1.1 Introduction 173

11.1.2 Definition of the reference sequence 173

11.1.2.1 Symbol level 174

11.1.2.2 Frame level 175

11.1.3 Scattered pilot insertion 175

11.1.3.1 Locations of the scattered pilots 175

11.1.3.2 Amplitudes of the scattered pilots 177

11.1.3.3 Modulation of the scattered pilots 177

11.1.4 Continual pilot insertion 177

11.1.4.1 Locations of the continual pilots 177

11.1.4.2 Locations of additional continual pilots in extended carrier mode 177

11.1.4.3 Amplitudes of the continual pilots 178

11.1.4.4 Modulation of the continual pilots 178

11.1.5 Edge pilot insertion 178

11.1.6 P2 pilot insertion 178

11.1.6.1 Locations of the P2 pilots 178

11.1.6.2 Amplitudes of the P2 pilots 178

11.1.6.3 Modulation of the P2 pilots 179

11.1.7 Insertion of frame closing pilots 179

11.1.7.1 Locations of the frame closing pilots 179

11.1.7.2 Amplitudes of the frame closing pilots 179

11.1.7.3 Modulation of the frame closing pilots 179

11.1.8 Amplitudes of pilots in the presence of intentional power imbalance (SISO) 180

11.1.9 Modification of the pilots for MIxO 180

11.1.10 Amplitudes of pilots in the presence of intentional power imbalance (MIXO) 181

11.2 Dummy tone reservation 182

11.3 Mapping of data cells to OFDM carriers 182

11.4 IFFT - OFDM Modulation 183

11.4.1 eSFN predistortion 185

11.5 PAPR reduction 186

11.5.1 Active constellation extension (ACE) 186

11.5.2 PAPR reduction using tone reservation 188

11.5.2.1 Algorithm of PAPR reduction using tone reservation 188

11.6 Guard interval insertion 190

11.7 P1 symbol insertion 191

11.7.1 P1 symbol overview 191

11.7.2 P1 symbol description 191

11.7.2.1 Carrier distribution in P1 symbol 192

11.7.2.2 Modulation of the active Carriers in P1 193

11.7.2.3 Boosting of the active Carriers 195

11.7.2.4 Generation of the time domain P1 signal 196

11.7.2.4.1 Generation of the main part of the P1 signal 196

11.7.2.4.2 Frequency-shifted repetition in guard intervals 196

11.7.3 Additional P1 (aP1) symbol 196

11.7.3.1 aP1 symbol overview 196

11.7.3.2 aP1 symbol description 197

11.7.3.2.1 aP1 scrambling sequence 197

11.7.3.2.2 Frequency-shifted repetition in guard intervals 198

12 Spectrum characteristics 198

Annex A (normative): Splitting of input MPEG-2 TSs into the data PLPs and common PLP of a group of PLPs 201

A.1 Overview 201

A.2 Splitting of input TS into a TSPS stream and a TSPSC stream 202

A.2.1 General 202

A.2.2 TS packets that are co-timed and identical on all input TSs of the group before the split 203

A.2.3 TS packets carrying Service Description Table (SDT) and not having the characteristics of category (1) 203

A.2.4 TS packets carrying Event Information Table (EIT) and not having the characteristics of category (1) 205

A.2.4.1 Required operations 205

A.2.4.2 Conditions 205

A.3 Receiver Implementation Considerations 207

Annex B (informative): Allowable sub-slicing values 210

Annex C (normative): Input stream synchronizer and receiver buffer model 211

C.1 Input stream synchronizer 211

C.2 Receiver buffer model 213

C2.1 Modelling of the PLP cell streams 214

C.2.2 Decoding rate limit 217

C.2.3 De-jitter buffer 218

Annex D (normative): Calculation of the CRC word 219

Annex E: 220

Addresses of parity bit accumulators for Nldpc = 16 200 220

Annex F (normative): Addresses of parity bit accumulators for Nldpc = 4 320 225

Annex G (informative): 226

Constellation diagrams for uniform, non-uniform and hierarchical constellations 226

Annex H (normative): Locations of the continual pilots 234

Annex I (normative): Reserved carrier indices for PAPR reduction 237

Annex J (informative): Pilot patterns 238

Part II: MIMO profile 244

13 DVB-NGH MIMO system definition 245

13.1 System overview and architecture 245

13.1.1 Bit interleaved coding and modulation, MISO and MIMO precoding 245

13.1.2 FEC encoding and interleaving inside a FEC block 246

13.1.3 Modulation and component interleaving 246

13.1.4 Time interleaving (inter-frame convolutional interleaving plus intra-frame block interleaving) 246

13.1.5 Frame building, frequency interleaving 247

14 Transmit/receive system compatibility 247

15 Bit interleaver 247

16 Complex symbol generation 250

17 Power imbalance 251

18 MIMO precoding 252

18.1 Spatial-Multiplexing Encoding 253

18.2 Phase Hopping 253

19 eSFN processing for MIXO 254

20 SISO/MIXO options for P1, aP1 and P2 symbols 254

21 Layer 1 signalling data specific for the MIMO profile 255

21.1 P1 and additional P1 signalling data 255

21.2 L1-PRE signalling data 256

21.3 L1-POST signalling data 257

21.3.1 L1-POST-configurable signalling data 257

21.3.2 L1-POST-dynamic signalling data 258

21.3.3 In-band signalling type A 258

Part III: Hybrid profile 259

22 DVB-NGH hybrid system definition 260

22.1 System overview and architecture 260

22.1.1 Bit-interleaved coding and modulation, MISO precoding 262

22.1.2 Frame building, frequency interleaving 263

22.1.3 OFDM generation 264

22.1.4 SC-OFDM generation 264

23 Input processing 265

24 Bit interleaved coding and modulation 265

24.1 Constellation mapping 265

24.2 Time Interleaver 265

24.3 Distributed and cross-polar MISO 267

25 Layer 1 signalling data specific for the hybrid profile 267

25.1 P1 and additional P1 signalling data 267

25.2 L1-PRE signalling data 268

25.3 L1-POST signalling data 268

25.3.1 L1-POST configurable signalling data 268

25.3.2 L1-POST dynamic signalling data 269

25.3.3 In-band signalling type A 269

26 Frame Builder 270

26.1 SC-OFDM 270

26.1.1 NGH hybrid SC-OFDM frames 270

26.1.1.1 Duration of the NGH hybrid SC-OFDM frame 270

26.1.1.2 Capacity and structure of the NGH hybrid SC.-OFDM frame 270

26.1.2 Frequency interleaver 272

27 OFDM Generation 272

28 SC-OFDM generation 274

28.1 Spreading 274

28.2 Pilot insertion 275

28.2.1 Introduction 275

28.2.2 Definition of the reference NGH hybrid sequence 275

28.2.3 Scattered pilot insertion 276

28.2.3.1 Locations of the scattered pilots 276

28.2.3.2 Amplitudes of the scattered pilots 276

28.2.3.3 Modulation of the scattered pilots 277

28.3 IFFT – SC-OFDM modulation 277

28.4 Guard interval insertion 278

Annex K (informative): SC-OFDM pilot pattern 279

Annex L (informative): Receiver Buffer Model extension 280

Part IV: Hybrid MIMO profile 281

29 DVB-NGH hybrid MIMO system definition 282

29.1 System overview and architecture 282

29.1.1 Hybrid MIMO SFN 282

29.1.2 Hybrid MIMO MFN 282

29.1.3 Time interleaving 282

30 Hybrid MIMO SFN 283

30.1 Transmit/receive system compatibility 283

30.2 Operational SFN modes 283

30.3 Power imbalance cases 284

31 Hybrid MIMO MFN 285

31.1 Transmit/receive system compatibility 285

31.2 Operational MFN modes 285

31.3 Spatial Multiplexing encoding for SC-OFDM waveform for rate 2 satellite MIMO 286

32 Layer 1 signalling data for the hybrid MIMO profile 287

32.1 P1 and additional P1 signalling data 287

32.2 L1-PRE signalling data 288

32.3 L1-POST signalling data 289

32.3.1.1 L1-POST configurable signalling data 289

32.3.2 L1-POST dynamic signalling data 290

32.3.3 In-band signalling type A 290

Annex M (informative): SC-OFDM pilot pattern 291

Annex N (informative): Rate-2 transmission with one transmit antenna 292

N.1.1 Overview 292

N.1.2 Block diagram 292

N.1.3 VMIMO processing 292

N.1.4 Parameter setting 293

N.1.5 Phase Hopping 293

N.1.6 Miscellaneous 293

History 295

Intellectual Property Rights

IPRs essential or potentially essential to the present document may have been declared to ETSI The

information pertaining to these essential IPRs, if any, is publicly available for ETSI members and

non-members, and can be found in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially

Essential, IPRs notified to ETSI in respect of ETSI standards", which is available from the ETSI Secretariat

Latest updates are available on the ETSI Web server (http://ipr.etsi.org)

Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI No guarantee can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates

on the ETSI Web server) which are, or may be, or may become, essential to the present document

Foreword

This final draft European Standard (EN) has been produced by Joint Technical Committee (JTC) Broadcast of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI), and is now submitted for the ETSI

standards One-step Approval Procedure

NOTE: The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in

the specific field of broadcasting and related fields Since 1995 the JTC Broadcast became a tripartite body by including in the Memorandum of Understanding also CENELEC, which is responsible for the standardization of radio and television receivers The EBU is a professional association of broadcasting organizations whose work includes the co-ordination of its

members' activities in the technical, legal, programme-making and programme-exchange domains The EBU has active members in about

60 countries in the European broadcasting area; its headquarters is in Geneva

European Broadcasting Union

CH-1218 GRAND SACONNEX (Geneva)

consumers DVB standards cover all aspects of digital television from transmission through interfacing, conditional access and interactivity for digital video, audio and data The consortium came together in 1993

to provide global standardisation, interoperability and future proof specifications

Proposed national transposition dates

Date of latest announcement of this EN (doa): 3 months after ETSI publication Date of latest publication of new National Standard

or endorsement of this EN (dop/e): 6 months after doa

Date of withdrawal of any conflicting National Standard (dow): 6 months after doa

1 Scope

The present document describes the next generation transmission system for digital terrestrial and hybrid (combination of terrestrial with satellite transmissions) broadcasting to handheld terminals It specifies the entire physical layer part from the input streams to the transmitted signal This transmission system is intended for carrying Transport Streams or generic data streams feeding linear and non-linear applications like television, radio and data services

The scope is as follows:

 it gives a general description of the transmission system for digital terrestrial and hybrid

broadcasting to handheld terminals;

 it specifies the digitally modulated signal in order to allow compatibility between pieces of

equipment developed by different manufacturers This is achieved by describing in detail the signal processing at the modulator side, while the processing at the receiver side is left open to different implementation solutions However, it is necessary in this text to refer to certain aspects of

reception

The standard consists of four parts each covering a different structure of the transmitter network:

 Base profile (profile I): Covers sheer terrestrial transmission with single and multi-aerial

structures that require only a single aerial and tuner on the receiver side

 MIMO profile (profile II): Covers sheer terrestrial transmission with multi-aerial structures

on both ends Terminals suitable for this profile need to employ two tuners as well

 Hybrid profile (profile III): Covers a combination of terrestrial and satellite transmissions that

requires only a single tuner on receiver side

Hybrid MIMO profile (profile IV): Covers a combination of terrestrial and satellite transmission requiring a double aerial and tuner set-up on receiver side Once again, a part of the configurations can be handled by profile II receivers, other configurations require a special hybrid MIMO receiver.The present document describes the base profile in full detail For the MIMO and hybrid profiles only the differences between those and the base profile are described, i.e additional functional blocks and parameter settings and those that are permitted in the MIMO or hybrid profile The hybrid MIMO profile is not formulated solely as a list

of differences to the other three profiles Instead it defines how previously-described elements are to be combined to provide hybrid MIMO transmission, as well as introducing profile-specific information

Functional blocks and settings that are the same as in the base profile are not described again, but can be derived from the base profile

2 References

References are either specific (identified by date of publication and/or edition number or version number)

or non-specific For specific references, only the cited version applies For non-specific references, the latest version of the reference document (including any amendments) applies

Referenced documents which are not found to be publicly available in the expected location might be found at http://docbox.etsi.org/Reference

NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot

guarantee their long term validity

2.1 Normative references

The following referenced documents are necessary for the application of the present document

[1] ISO/IEC 13818-1: "Information technology - Generic coding of moving pictures

and associated audio information: Systems"

[2] ETSI EN 300 468: "Digital Video Broadcasting (DVB); Specification for Service

Information (SI) in DVB systems"

[3] ETSI TS 102 606-1 and -2: "Digital Video Broadcasting (DVB); Generic Stream

Encapsulation (GSE) Protocol"

[4] ETSI TS 102 992: "Digital Video Broadcasting (DVB); Structure and modulation

of optional transmitter signatures (T2-TX-SIG) for use with the DVB-T2 second generation digital terrestrial television broadcasting system"

2.2 Informative references

The following referenced documents are not necessary for the application of the present document but they assist the user with regard to a particular subject area

[i.1] ETSI EN 302 755: "Digital Video Broadcasting (DVB); Frame structure channel

coding and modulation for a second generation digital terrestrial television broadcasting system (DVB-T2)"

[i.2] ETSI EN 102 831: "Digital Video Broadcasting (DVB); Implementation guidelines

for a second generation digital terrestrial television broadcasting system T2)"

(DVB-[i.3] ETSI EN 102 773: " Digital Video Broadcasting (DVB); Modulator Interface

(T2-MI) for a second generation digital terrestrial television broadcasting system (DVB-T2)"

[i.4] NGH System Specification

3 Definitions, symbols and abbreviations

3.1 Definitions

In this entire specification, the following terms and definitions apply:

0xkk: digits 'kk' should be interpreted as a hexadecimal number

active cell: OFDM cell carrying a constellation point for L1 signalling or a PLP

anchor PLP: An anchor PLP is the PLP of a PLP cluster which shall be always decoded in order for the

receiver to play-out the service partially or fully, i.e with part or all of the service components respectively The anchor PLP carries the in-band signalling for all PLPs (anchor and associated PLPs) in the given PLP

cluster

aP1 symbol: additional P1 symbol that carries S3 and S4 signalling fields and is located right after the P1

symbol

associated PLP: An associated PLP is a PLP associated with an anchor PLP in a given PLP cluster The

associated PLP carries a service component of the full service carried by the given PLP cluster An

associated PLP does not carry in-band signalling, which in turn is carried by the anchor PLP of the given PLP

cluster

auxiliary stream: sequence of cells carrying data of as yet undefined modulation and coding, which may be

used for future extensions or as required by broadcasters or network operators

baseband frame: set of Kbch bits which form the input to one FEC encoding process (BCH and LDPC

encoding)

common PLP: PLP having one slice per logical frame, transmitted after the L1-POST signalling, which may

contain data shared by multiple PLPs

data PLP: PLP of type 1, type 2, type 3 or type 4

data cell: OFDM cell which is not a pilot or tone reservation cell (may be an unmodulated cell in the frame

closing symbol)

data symbol: OFDM symbol in an NGH frame which is not a P1 or P2 symbol

div: integer division operator, defined as:

dummy cell: OFDM cell carrying a pseudo-random value used to fill the remaining capacity not used for L1

signalling, PLPs or Auxiliary Streams

elementary block of frames: block of not more than four NGH frames belonging to the same NGH profile

and building an instance of the frame type sequence of the related NGH system (e.g

SISO/SISO/SISO/MIMO)

elementary period: time period which depends on the system bandwidth and is used to define the other

time periods in the NGH system

FEC block: set of Ncells OFDM cells carrying all the bits of one LDPC FECFRAME

FEC chain: The part of the BICM block reaching from the FEC encoder to the I/Q component interleaver (if

present, otherwise to the cell interleaver) for PLPs and the cell mapper for L1 signalling

FECFRAME: set of Nldpc (16 200 or 4 320) bits from one LDPC encoding operation

FEF interval:

FEF part: part of the super-frame between two NGH frames which contains FEFs

NOTE: A FEF part always starts with a P1 symbol The remaining contents of the FEF part should be

ignored by a DVB-NGH receiver and may contain further P1 symbols

FFT size: nominal FFT size used for a particular mode, equal to the active symbol period Ts expressed in

cycles of the elementary period T

for i=0 xxx-1: the corresponding signalling loop is repeated as many times as there are elements of the

loop

NOTE: If there are no elements, the whole loop is omitted

frame closing symbol: OFDM symbol with higher pilot density used at the end of an NGH frame in certain

combinations of FFT size, guard interval and scattered pilot pattern

hybrid combining:

Im(x): imaginary part of x

input stream: A stream of data for an ensemble of services delivered to the end users by the NGH system

An input stream may be structured into a number of logical channel groups defined in accordance with the service requirements

interleaving frame: unit over which dynamic capacity allocation for a particular PLP is carried out, made up

of an integer, dynamically varying number of FEC blocks and having a fixed relationship to the logical frames

NOTE: The interleaving frame may be mapped directly to one logical frame or may be mapped to

multiple logical frames It may contain one or more TI blocks

L1-POST signalling: signalling carried in the beginning of a logical frame providing more detailed L1

information about the NGH system and the PLPs, L1-POST signalling consists of a configurable and a

dynamic part

L1-POST configurable signalling: L1 signalling consisting of parameters which remain the same for the

duration of one logical super-frame

L1-POST dynamic signalling: L1 signalling consisting of parameters which may change from logical frame to

logical frame within the same logical super-frame

L1-PRE signalling: signalling carried in the P2 symbols having a fixed size, coding and modulation, including

basic information about the NGH system as well as information needed to decode the L1-POST signalling NOTE: Some fields of the L1-PRE signalling may change from one NGH frame to another within the

same NGH super-frame, for example, L1_POST_DELTA for logical channel types B and C

logical channel: A flow of logical super-frames for the transport of data over a given repeating pattern of RF

channels in the NGH system

logical channel group: A group of logical channels such that the NGH frames which carry the logical frames

of one logical channel in the group are separable in time from the NGH frames which carry the logical frames of another logical channel in the same group

logical frame: A container with a fixed number of QAM cells and a given structure for the carriage of data

into the NGH frames

logical super-frame: An entity composed of a number of logical frames The logical configurable signalling

information may only change at the boundaries of two logical super-frames

MIXO: either MISO or MIMO

MIXO group: group (1 or 2) to which a particular transmitter in a MIXO network belongs, determining the

type of processing which is performed to the data cells and the pilots

NOTE: Signals from transmitters in different groups will combine in an optimal manner at the

x mod

NGH frame: fixed physical layer TDM frame that is further divided into variable size sub-slices An NGH

frame starts with one P1 symbol, followed for a part of the frame types by an additional P1 (aP1) symbol and always one or multiple P2 symbols carrying the L1-PRE information

NGH profile: subset of all configurations allowed by the related part of the present document

NOTE: The present document defines a base profile, a MIMO profile, a hybrid profile and a hybrid MIMO profile

NGH system: second generation terrestrial broadcast system whose input is one or more TS, GCS or GSE

streams and whose output is an RF signal

NOTE: The NGH system:

 means an entity where one or more PLPs are carried, in a particular way, within a DVB-T2 signal on one or more frequencies;

 is unique within the NGHnetwork and it is identified with NGH_system_id Two NGH systems with the same NGH_system_id and network_id have identical physical layer structure and configuration, except for the cell_id which may differ;

 is transparent to the data that it carries (including Transport Streams and services)

NGH_SYSTEM_ID: this 16-bit field identifies uniquely the NGH system within the DVB network (identified

by NETWORK_ID)

NGH super-frame: set of NGH frames consisting of a particular number of consecutive NGH frames

NOTE: A super-frame may in addition include FEF parts

NGH signal: signal belonging to a particular profile of the present document (NGH base profile, NGH MIMO

profile, NGH hybrid profile or NGH hybrid MIMO profile profile) and consisting of the related NGH frame types, including any FEF parts

NOTE: A composite RF signal may be formed comprising two or more NGH signals, where each NGH

signal has the others in its FEF parts

nn D : digits 'nn' should be interpreted as a decimal number

normal symbol: OFDM symbol in an NGH frame which is not a P1, an aP1, a P2 or a frame closing symbol OFDM cell: modulation value for one OFDM carrier during one OFDM symbol, e.g a single constellation

point

OFDM symbol: waveform Ts in duration comprising all the active carriers modulated with their

corresponding modulation values and including the guard interval

P1/aP1 signalling: signalling carried by the P1/aP1 symbol(s) and used to identify the basic mode of the

NGH frame, the aP1 symbol is present only in a part of the defined frame types

P1 symbol: fixed pilot symbol that carries S1 and S2 signalling fields and is located in the beginning of the

frame within each RF-channel

NOTE: The P1 symbol is mainly used for fast initial band scan to detect the NGH signal, its timing,

frequency offset and FFT-size

P2 symbol: pilot symbol located right after P1 (aP1 if present) with the same FFT size and guard interval as

the data symbols

NOTE: The number of P2 symbols depends on the FFT-size The P2 symbols are used for fine

frequency and timing synchronization as well as for initial channel estimate P2 symbols carry

L1-PRE signalling information and may also carry data

PLP_ID: this 8-bit field identifies uniquely a PLP within the NGH system, identified with the NGH_system_id

NOTE: The same PLP_ID may occur in one or more logical frames of the logical super-frame

PLP cluster: A PLP cluster is the set of up to 4 PLPs that carry a particular TS input stream or a collection of

GS input streams with the same STREAM_GROUP_ID

physical layer pipe: physical layer TDM channel that is carried by the specified sub-slices

NOTE: A PLP may carry one or multiple services

Re(x): real part of x

reserved for future use: not defined by the present document but may be defined in future revisions of the

present document

NOTE: Further requirements concerning the use of fields indicated as "reserved for future use" are

given in clause Error! Reference source not found

slice: set of all cells of a PLP which are mapped to a particular NGH frame

NOTE: A slice may be divided into sub-slices

sub-slice: group of cells from a single PLP, which before frequency interleaving, are allocated to active

OFDM cells with consecutive addresses over a single RF channel

time interleaving block (TI-block): set of cells within which time interleaving is carried out, corresponding

to one use of the time interleaver memory

type 1 PLP: PLP having one slice per logical frame, transmitted before any type 2 PLPs

type 2 PLP: PLP having two or more sub-slices per logical frame, transmitted after any type 1 PLPs

type 3 PLP: PLP carrying O-LSI data and being located at the end of the logical frame

type 4 PLP: PLP carrying H-LSI data and being transmitted via hierarchical modulation over a dedicated type

1 PLP

uninterleaved logical frame: Collection of all PLPs whose cells are transmitted in a sequence of interleaved

logical frames

3.2 Symbols

For the purposes of the present document, the following symbols apply:

 Exclusive OR / modulo-2 addition operation

 Guard interval duration

MOD, MOD(i) number of transmitted bits per constellation symbol (for PLP i)

1 TR Vector containing ones at positions corresponding to reserved carriers

and zeros elsewhere

a m,l,p Frequency-Interleaved cell value, cell index p of symbol l of NGH frame

m

A CP Amplitude of the continual pilot cells

AP2 Amplitude of the P2 pilot cells

ASP Amplitude of the scattered pilot cells

ß Power imbalance parameter for two antennas transmission

b i

b BS,j Bit j of the BB scrambling sequence

b e,do Output bit of index do from substream e from the bit-to-sub-stream

demultiplexer

C/N Carrier-to-noise power ratio

C/N+I Carrier-to-(Noise+Interference) ratio

Cbal(m) Value to which bias balancing cells are set for NGH frame m

)

(

bal m

C Desired value for the bias balancing cells in NGH frame m to

approximately balance the bias

Cbias(m) Bias in coded and modulated L1 signalling for NGH frame m before

applying the L1-ACE algorithm

Cbias_L1_ACE(m) Value of Cbias(m) after being reduced by the correction to be applied

by the bias balancing cells

)

(

bias m

C Residual bias in the modulated cells of the L1 signalling for NGH frame

m after correction by the L1-ACE algorithm

C data Number of active cells in one normal symbol

CFC Number of active cells in one frame closing symbol

Cim(m) Imaginary part of Cbias(m)

CL1_ACE_MAX Maximum correction applied by L1-ACE algorithm

C LSI Number of local service cells

C P2 Number of active cells in one P2 symbol

in NGH frame m by L1-ACE algorithm

NGH frame m by L1-ACE algorithm

Cre(m) Real part of Cbias(m)

CSS S1,i Bit i of the S1 modulation sequence

CSS S2,i Bit i of the S2 modulation sequence

C tot Number of active cells in one NGH frame

DBC Number of cells occupied by the bias balancing cells and the

associated dummy cells

Di Number of cells mapped to each NGH frame of the Interleaving Frame

for PLP i

Di,aux Number of cells carrying auxiliary stream i in the NGH frame

D i,j Number of cells mapped to each NGH frame for PLP i of type j

each TI-block

D L1 Number of OFDM cells in each NGH frame carrying L1 signalling

DL1post Number of OFDM cells in each NGH frame carrying L1-post signalling

DL1pre Number of OFDM cells in each NGH frame carrying L1-pre signalling

of TI-block s of Interleaving Frame n

D PLP Number of OFDM cells in each NGH frame available to carry PLPs

d r,q Cell interleaver output for cell q of FEC block r

Dx Difference in carrier index between adjacent scattered-pilot-bearing

fc Centre frequency of the RF signal

fq Constellation point normalized to mean energy of 1

fq r,q Data cell input to the cell interleaver from the FEC block of

incremental index r within each TI-block

fSh Frequency shift for parts 'B' and 'C' applied to the P1 and aP1 symbols

Φk eSFN predistortion term

g1(x), g2(x),  …,  g12(x) polynomials to obtain BCH code generator polynomial

gq OFDM cell value after constellation rotation and I/Q component

interleaving

H0(p) Frequency interleaver permutation function, element p, for even

symbols

H1(p) Frequency interleaver permutation function, element p, for odd

symbols

IJUMP, IJUMP(i) Frame interval: difference in frame index between successive NGH

frames to which a particular PLP is mapped (for PLP i)

i j BCH codeword bits which form the LDPC information bits

k' Carrier index relative to the centre frequency

Kbch number of bits of BCH uncoded Block

Kext Number of carriers added on each side of the spectrum in extended

carrier mode

Kldpc number of bits of LDPC uncoded Block

Kmax Carrier index of last (highest frequency) active carrier

Kmin Carrier index of first (lowest frequency) active carrier

Kmod Modulo value used to calculate continual pilot locations

kp1(i) Carrier index k for active carrier i of the P1 symbol

K post Length of L1-post signalling field including the padding field

field

K pre Information length of the L1-pre signalling

K sig Number of signalling bits per FEC block for L1-pre- or L1-post signalling

Ktotal Number of OFDM carriers

l Index of OFDM symbol within the NGH frame

L Maximum value of real or imaginary part of the L1-post constellation

Ldata Number of data symbols per NGH frame including any frame closing

symbol but excluding P1 and P2

LF Number of OFDM symbols per NGH frame excluding P1

Lim(m) Correction level for the imaginary part of the post used in the

L1-ACE algorithm

Lnormal Number of normal symbols in a NGH frame, i.e not including P1, P2 or

any frame closing symbol

Lpre(m) Correction level for the L1-pre used in the L1-ACE algorithm

L r (q) Cell interleaver permutation function for FEC block r of the TI-block

Lre_post(m) Correction level for the real part of the L1-post used in the L1-ACE

Mbit/s Data rate corresponding to 106 bits per second

MIR Number of incremental redundancy parity bits

M j Number of PLPs of type j in the NGH system

Mlarge

Mmax Sequence length for the frequency interleaver

Msmall

M TI Maximum number of cells required in the TI memory

n Interleaving Frame index within the super-frame

Nbch number of bits of BCH coded Block

Ncells, Ncells(i) Number of QAM cells per FEC Block (for PLP i)

N D Number of rotation dimensions

Ndata Number of data cells in an OFDM symbol (including any unmodulated

data cells in the frame closing symbol)

Ndummy Number of dummy cells in the NGH frame

N EBF Number of EBFs in a super-frame

N F Number of NGH frames in an EBF

N FEC_TI (n,s) Number of FEC blocks in TI-block s of Interleaving Frame n

NFEC_TI_MAX

NFEF Number of FEF parts in one super-frame

Nim(m) Number of L1-post cells available for correction by the imaginary part

of the L1-ACE algorithm

N IU Number of interleaver units, into which each FEC block is partitioned

N K Number of TFS cycles, over which a FEC block is time-interleaved

N L1 Total number of bits of L1 signalling

Nlarge

Nldpc number of bits of LDPC-coded block

Nldpc2 Number of bits of extended 4k LDPC-coded block

Nldpc_parity_ext_4k Number of parity bits of the extended 4k LDPC code

NMUs,PLP Required number of memory units in TI for one PLP

NP2 Number of P2 symbols per NGH frame

N pad Number of BCH bit-groups in which all bits will be padded for L1

signalling

NPN Length of the frame-level PN sequence

N post Length of punctured and shortened LDPC codeword for L1-post

signalling

Npre(m) Number of L1-PRE cells available for correction by the L1-ACE

algorithm

n pre Number of L1-PRE sub-blocks, which are carried by consecutive NGH

frames

N punc Number of LDPC parity bits to be punctured

signalling

N r Number of bits in Frequency Interleaver sequence

N R Number of rows of I/Q component interleaving matrix

Nre(m) Total number of L1 cells available for correction by the real part of the

NRF Number of RF channels used in a TFS system

Nsub-slices Number of sub-slices per NGH frame on each RF channel

Nsub-slices_total Number of sub-slices per NGH frame across all RF channels

demultiplexer

N NGH Number of NGH frames in a super-frame

NTI Number of TI-blocks in an Interleaving Frame

p Data cell index within the OFDM symbol in the stages prior to insertion

of pilots and dummy tone reservation cells

p 1 j j-th parity bit group in the first parity part for additional parity

generation of L1-POST

p 2 j j-th parity bit group in the second parity part for additional parity

generation of L1-POST

p1(t) Time-domain complex baseband waveform for the P1 signal

p1A(t) Time-domain complex baseband waveform for part 'A' of the P1 signal

P I , P I (i) Number of NGH frames to which each Interleaving Frame is mapped

(for PLP i)

pnl Frame level PN sequence value for symbol l

q Index of cell within coded and modulated LDPC codeword

Qldpc Code-rate dependent LDPC constant

Qldpc1 Number of parity bit groups in the first parity part for additional parity

generation

Qldpc2 Number of parity bit groups in the second parity part for additional

parity generation

r FEC block index within the TI-block

r i QPSK output symbols of L1-PRE

R’i Value of element i of the frequency interleaver sequence following bit

permutations

R'i Value of element i of the frequency interleaver sequence prior to bit

permutations

r l,k Pilot reference sequence value for carrier k in symbol l

R RQD Complex phasor representing constellation rotation angle

s Index of TI-block within the Interleaving Frame

S CHE Number of additional symbols needed for channel estimation when

hopping between RF signals

S i Element i of cell interleaver PRBS sequence

S tuning Number of symbols needed for tuning when hopping between RF

signals

T Elementary time period for the bandwidth in use

tc Column-twist value for column c

T EBF Duration of one EBF

T F Duration of one NGH frame

TFEF Duration of one FEF part

T P Time interleaving period

T P1 Duration of the P1 symbol

TP1A Duration of part 'A' of the P1 signal

TP1B Duration of part 'B' of the P1 signal

TP1C Duration of part 'C' of the P1 signal

TS Total OFDM symbol duration

T Duration of one super-frame

TU Active OFDM symbol duration

u i Parity-interleaver output bits

v i column-twist-interleaver output bits

w i Bit i of the symbol-level reference PRBS

  x Round towards minus infinity: the most positive integer less than or

equal to x

x

  Round towards plus infinity: the most negative integer greater than or

equal to x x* Complex conjugate of x

X j The set of bits in group j of BCH information bits for L1 shortening

NGH frame m

y i,q Bit i of cell word q from the bit-to-cell-word demultiplexer

z q Constellation point prior to normalization

πp Permutation operator defining parity bit groups to be punctured for L1

signalling

π1p Puncturing pattern order of first parity bit grou

π2

p Puncturing pattern order of second parity bit group

πs Permutation operator defining bit-groups to be padded for L1

3.3 Abbreviations

For the purposes of the present document, the following abbreviations apply:

16-QAM Uniform 16-ary Quadrature Amplitude Modulation

256-QAM Uniform 256-ary Quadrature Amplitude Modulation

64-QAM Uniform 64-ary Quadrature Amplitude Modulation

ACM Adaptive Coding and Modulation

BB BaseBand

BBF BaseBand Frame

BCH Bose-Chaudhuri-Hocquenghem multiple error correction binary block code

BICM Bit Interleaved Coding and Modulation

BPSK Binary Phase Shift Keying

CBR Constant Bit Rate

CCM Constant Coding and Modulation

CI Cell Interleaver

CRC Cyclic Redundancy Check

D Decimal notation

DAC Digital to Analogue Conversion

DBPSK Differential Binary Phase Shift Keying

DFL Data Field Length

DNP Deleted Null Packets

DVB Digital Video Broadcasting project

DVB-NGH DVB-NGH System

NOTE: Specified in EN 303 105

EBF Elementary Block of NGH Frames

EBU European Broadcasting Union

EIT Event Information Table

eSFN Enhanced Single Frequency Network

eSM Enhanced Spatial Multiplexing

FEC Forward Error Correction

FEF Future Extension Frame

FFT Fast Fourier Transform

FIFO First In First Out

GCS Generic Continuous Stream

ISCR Input Stream Clock Reference

ISI Input Stream Identifier

ISSY Input Stream SYnchronizer

ISSYI Input Stream SYnchronizer Indicator

LSB Least Significant Bit

LSI Local Service Insertion

MFN Multi-Frequency Network

MIMO Multiple Input Multiple Output

NOTE: Meaning multiple transmitting and multiple receiving antennas MIS Multiple Input Stream

MISO Multiple Input, Single Output

NOTE: Meaning multiple transmitting antennas but one receiving antenna MODCOD MODulation and CODing

MODCODTID MODulation, CODing and Time Interleaving Depth

MPEG Moving Pictures Experts Group

MSB Most Significant Bit

NOTE: In DVB-NGH the MSB is always transmitted first

MSS Modulation Signalling Sequences

O-LSI Orthogonal Local Service Insertion

O-UPL Original User Packet Length

PAPR Peak to Average Power Ratio

PCR Programme Clock Reference

PER (MPEG TS) Packet Error Rate

PH Phase Hopping

PID Packet IDentifier

PLL Phase Locked Loop

PLP Physical Layer Pipe

PRBS Pseudo Random Binary Sequence

QEF Quasi Error Free

QPSK Quaternary Phase Shift Keying

RF Radio Frequency

R-PLP Regional service PLP

SDT Service Description Table

SFN Single Frequency Network

SIS Single Input Stream

SISO Single Input Single Output

NOTE: Meaning one transmitting and one receiving antenna

SM Spatial Multiplexing

SoAC Sum of AutoCorrelation

TDI Time De-Interleaving

TDM Time Division Multiplex

TF Time/Frequency

TFS Time-Frequency Slicing

TS Transport Stream

TSPS Transport Stream Partial Stream

TSPSC Transport Stream Partial Stream Common

TTO Time To Output

TV TeleVision

UP User Packet

UPL User Packet Length

VCM Variable Coding and Modulation

VMIMO Virtual MIMO

Part I: Base profile

4 System overview and architecture

The top level NGH system architecture is represented in figure 1 Services or service components are embedded into Transport Streams (TS) [1] or Generic Streams [3] which are then carried in individual Physical Layer Pipes (PLPs) The PLPs are mapped onto logical channels (LC), which are then transmitted in NGH physical frames according to a fixed schedule The sequence of NGH frames carrying a logical channel may be transmitted over a single or multiple RF frequencies

Transmission Layer (Physical layer)

RF1

RF2

RF N

Scheduler / Multiplexer

LC 1

Transport Layer Service Layer

Component 1 Component 2

Component 1

Component 1 Component 2 Component 3

PLP 1 PLP 2 PLP 3

Service 1

Service 2

Service K

Inc Video codec

(e.g H.264 / SVC) Transport streams(e.g TS; IP/GSE) DVB-NGH Signal(PHY Frames)

Stream (TS) / Stream Group (GS) 1

Stream (TS) / Stream Group (GS) L

COM PLP

LC M

PLP 1 COM PLP

Control

Control

LC 2

PLP 1

Figure 1: Top level NGH system architecture

This specification is restricted to the physical layer The overall system specification is described in [i.4]

Input processing

Bit-interleaved coding and modulation, MISO precoding

Frame building OFDM generation

TS or GSE

inputs

Signal on air

Figure 2: High level NGH phy layer block diagram

Figure 2 shows the NGH physical layer block diagram which comprises four main building blocks The input

to the NGH system shall consist of one or more logical data streams One logical data stream is carried by one Physical Layer Pipe (PLP) The PLP specific input processing stage (see also figures 3-5) comprises the mode adaptation as well as the encapsulation into baseband frames (BBFs) BBFs are then FEC encoded and interleaved at FEC frame level as well as - after being modulated onto a QAM constellation – interleaved on component, time and frequency level (figure 6) The frame building block (figure 7) comprises the

generation of the NGH logical and physical frames which are finally OFDM modulated and transmitted on a single or multiple (in case of TFS usage) RF frequencies (figure 9) In the latter case the system is designed

to allow continuous reception of a service with a single tuner

4.1 Input processing

Input interface

CRC-8 encoder

BB Header insertion

Padding insertion

BB Scrambler

To BICM module

Single

input

stream

Signalling generation

L1-PRE

L1-POST

L1 Scrambler

To BICM module

Figure 3: System block diagram, input processing module for input mode 'A' (single PLP)

Input interface

Input Stream Synchroniser

Compensating delay

deletion

CRC-8 encoder

BB Header insertion

Input interface

Input Stream Synchroniser

Compensating delay

deletion

CRC-8 encoder

BB Header insertion

Input interface

Input Stream Synchroniser

Compensating delay

deletion

CRC-8 encoder

BB Header insertion

Multiple

input

streams

To stream adaptation

Figure 4: Mode adaptation for input mode 'B' (multiple PLP)

In-band signaling

or (if relevant) padding insertion

BB Scrambler

BB Scrambler

BB Scrambler

Logical frame delay

In-band signaling

or (if relevant) padding insertion

Logical frame delay

In-band signaling

or (if relevant) padding insertion

To BICM module

Logical frame m

Logical frame m+1

L1-DYNAMIC PLP0 (m)

L1-DYNAMIC PLPn (m) L1-DYNAMIC PLP1 (m)

L1-POST

Figure 5: Stream adaptation for input mode 'B' (multiple PLP)

4.1.1 Mapping of input streams onto PLPs

Input data in the form of TS packets or GS data (e.g GSE packets) enter the NGH system in parallel with one input stream per PLP branch For input streams that are Transport Streams TS data that is common to all TSs and time synchronized are extracted (and replaced by null packets in the original stream) and put into a dedicated partial transport for common data (TSPSC) stream that is transmitted in a common PLP Each input TS may also be split into several partial transport streams (TSPS), which are transmitted in dedicated data PLPs This may be used to send e.g service components in different PLPs, with potentially a different robustness using e.g a different MODCODTID per service component

The sum of the coded bit rates (i.e bit rates at the output of the LDPC encoder) of a PLP cluster shall not exceed 12 Mbit/s A PLP cluster is the set of up to 4 PLPs that carry a particular TS input stream or a

collection of GS input streams with the same stream group id

4.1.2 Encapsulation into baseband frames

The input data is put into the payload of baseband frames (BBFs), which also have a header with a fixed size

for a given mode The BBFs may also have some padding in the end The first BBF in each interleaving frame

(see below) may carry some in-band signaling (IBS) of type A (dynamic info used to find PLPs) and type B (ISSY and other info to help the receiver with e.g buffer management)

4.2 Bit-interleaved coding and modulation, MISO precoding

FEC encoding

(16K LDPC/BCH)

Bit interleaver

Demux bits to cells

Map cells to constellations

Cell interleaver

Inter-frame convolutional and intra-frame block interleaving

To logical frame builder

PLP0

FEC encoding

(16K LDPC/BCH)

Bit interleaver

Demux bits to cells

Map cells to constellations

Cell interleaver PLP1

FEC encoding

(16K LDPC/BCH)

Bit interleaver

Demux bits to cells

Map cells to constellations

Cell interleaver PLPn

Constellation rotation

Constellation rotation

Constellation rotation

I/Q component interleaving

I/Q component interleaving

I/Q component interleaving

MISO precoding

Inter-frame convolutional and intra-frame block interleaving

MISO precoding

Inter-frame convolutional and intra-frame block interleaving

MISO precoding

Demux bits to cells

Map cells to constellations

Map cells to constellations

To logical frame builder

To NGH frame builder Scrambled

L1-POST

Scrambled

L1-PRE

MISO precoding

MISO precoding

Figure 6: Bit interleaved coding and modulation (BICM), MISO precoding

4.2.1 FEC encoding and interleaving inside a FEC block

The BBFs are FEC-encoded using a BCH code followed by a 16200 bit (16K) LDPC code (4K for PRE and

L1-POST) Bit interleaving is applied within the FEC block Bit interleaved FEC block bits are demultiplexed to

cell words and mapped to constellations points (cells) Cell interleaving is then applied within each FEC

block

4.2.2 Modulation and component interleaving

The constellation is either non-rotated (QPSK, 16-QAM, 64-QAM or 256-QAM), 2D-rotated (QPSK, 16-QAM,

64-QAM) or 4D-rotated (QPSK) For QPSK, 2D- and 4D-rotations are only specified for a subset of the code

rates In addition there are non-uniform constellations (NU-64-QAM and NU-256-QAM) NU-64-QAM is

either non-rotated or 2D-rotated NU-256-QAM is never rotated When constellation rotation is used, an

I/Q component interleaver is applied to the rotated real and imaginary constellation components (two

components with 2D rotation and four components with 4D rotation) whereby the components become

separated over the time interleaving depth, increasing the time diversity When TFS is used, these

components also appear on different RF channels, in order to increase frequency diversity

4.2.3 Formation of interleaving frames for each PLP

An integer number of FEC blocks from each PLP are collected into an interleaving frame This number of

FEC blocks in one interleaving frame can be different from PLP to PLP and over time and so is signaled for

each PLP An interleaving frame is either transmitted in one logical frame or is spread across more than one

logical frame thereby providing more time diversity for the FEC blocks of the PLP

4.2.4 Time interleaving (inter-frame convolutional interleaving plus

intra-frame block interleaving)

The time interleaver block spreads the cells of the FEC blocks for each interleaving frame over one or

multiple logical frames (LFs) Interleaving over multiple LFs is achieved by convolutional interleaving

referred to as inter-frame interleaving With or without inter-frame interleaving, the FEC block cells are

shuffled within each logical frame by block interleaving, which is referred to as intra-frame

interleaving Both convolutional and block interleaving together constitute the time interleaving Its configuration is PLP-specific If the time interleaver is configured to carry out exclusively intra-frame interleaving and no inter-frame interleaving, then the time interleaving becomes a sheer block interleaving

4.3 Frame building, frequency interleaving

Logical Frame builder

(assembles modulated cells of PLPs and L1-POST signalling into logical frames

Operates according to dynamic scheduling information produced by scheduler)

L1-PRE

Frequency interleaver

To OFDM generation

Assembly

of L1-POST cells

NGH Frame builder

(assembles modulated cells of logical frames and L1-PRE signalling into arrays corresponding to OFDM symbols

Operates according

to dynamic scheduling information produced by scheduler)

Assembly

of data PLP cells

Sub-slice processor

L1-POST

Logical frames

Figure 7: Frame builder

4.3.1 Formation of logical frames

The collection of time interleaving blocks that are simultaneously output are assembled in a logical frame The result of the time interleaving process is a sequence of cells for each PLP in each logical frame The cell sequences of the different PLPs in the logical frame are then combined in such a way that the cells of one PLP are followed by the cells of the second PLP etc With M PLPs we obtain therefore a vector with cells arranged in M  slices  (“bursts”),  i.e  with  one  slice  per  PLP  In  addition  subslicing  may  be  performed,  by  which each slice is divided into L smaller parts or sub-slices which are then distributed in time over the logical frame duration A logical channel (see clause 4.1.9) is derived from a sequence of logical frames With logical channel type D each slice is divided into the same number (one or more) of sub-slices per RF channel used by the logical channel In this case we have a matrix with one column per RF channel containg the logical frame cells of that RF channel

A logical frame consists of the following elements (in order):

The L1-POST is mandatory All of the other elements of the logical frame are optional, except that at least one of the PLP types 1, 2 and 3 must appear in each LF For LC type D the L1-POST is put in the beginning of all the columns of the above-mentioned matrix PLP type 4 only occurs in the presence of PLP type 1 which

it hierarchically modulates

Each LF in a logical super-frame of a given logical channel has a constant number of cells The number of logical frames in a logical super-frame of a given logical channel is signalled in L1-POST Because of bit rate variations of the incoming streams the resulting number of FEC block cells may vary somewhat across logical frames The statistical multiplexing of video streams can (and should) be organized in a way that the total number of cells remains constant rather than the total bit rate However, this process is not perfect and it is in general impossible to guarantee a constant number of FEC block cells per collection window After cell interleaving this means that there will also be some variations in the number of cells per LF In order to compensate for this a number of auxiliary stream cells and/or dummy cells are added each LF just before the occurrence of any PLPs of Type 3 (or in the end of the LF when there are no Type 3 PLPs) The number of auxiliary stream cells and/or dummy cells is signalled in the L1-POST dynamic signalling

At this point of the chain we have thus a sequence of logical frames, each containing a vector (matrix instead of a vector in the case of logical channel type D) of cells There is not yet any organization into OFDM symbols and carriers applied and the logical frame/logical channel concept does not require this – each logical frame is just a vector of cells (matrix with logical channel type D) Each logical frame within the current logical super-frame has the same size and the sequence of such logical frames and logical super-frames constitutes a logical channel (LC) For LCs of types A, B and C this is fully valid - in this case the receiver is able to receive and demodulate all cells of a logical channel (in LC type C using TFS/frequency hopping) since all cells of the LC always appear sequentially However, for LC type D the LF is composed of

N parallel vectors, when TFS is performed over N RF channels, which means that the logical channel in this case exists simultaneously on multiple RF channels The L1-POST signalling also appears for each of the parallel vectors

In this case (LC type  D)  the  N  vectors  of  the  matrix  are  processed  via  a  “shift-and-fold  procedure”,  which  ensures that the sub-slices of each PLP are spread in time in a way which allows a single tuner to receive the relevant PLP (or PLPs) via frequency hopping

4.3.2 Mapping of logical frames onto NGH frames

The way the logical channel cells are transmitted is that they use cell capacity in one or more RF channels, each having an OFDM-modulated NGH signal The NGH signal is composed of NGH frames, potentially with FEF gaps between them, divided into OFDM symbols and OFDM cells See also figure 8

Figure 8: Mapping of input stream FEC blocks to interleaving frames, logical frames and

NGH frames

Each physical layer frame begins with a P1 symbol (accompanied in some cases by an additional P1 symbol (aP1)), followed by a number of P2 symbols, depending on the applied FFT size In certain combinations of FFT size, guard interval and pilot patterns, the frame shall end with a frame closing symbol In addition to this, the physical frame incorporates scattered pilots and continual pilots amongst the data cells, which are the capacity units or the  “payload”  of  the  NGH  frames used to carry the logical channel cells Data cells are those cells in the NGH frame that are not occupied by any of the other components (P1/aP1, P2 pilots, frame closing pilots, scattered pilots, continual pilots, reserved tones) and therefore are available for transport of logical channel cells

A set of NGH frames constitutes a super-frame In a super-frame the NGH frames may be allocated to different logical frames and may also use different frame types (SISO, MISO), as indicated by the L1-PRE signalling of the NGH frame, which signals the composition of the NGH frame

The RF bandwidth, FFT size, guard interval (GI) and pilot pattern (PPx) may be different on different RF channels In addition, on a given RF channel the pilot pattern may be unique for all frames carrying a particular logical channel For a given PLP the MODCODTID (modulation/constellation, channel coding and time interleaving depth) is however given by the logical channel and not by the RF channel Please note again that the logical frames do not have anything to do with OFDM – they are just fixed-length (potentially parallel in case of LC type D) sequences of cells with no OFDM symbols or carriers involved!

A given RF channel has a fixed, well-determined cell capacity (cells per second) to carry LC cells When more than one logical channel is used, the NGH frames used to carry a particular logical channel also have a fixed, well-determined capacity A set of RF channels has a total cell capacity that is the sum of the cell capacities

of the individual RF channels This total cell capacity may be used by any number of logical channels and the cell rate of each logical channel must exactly match the available cell rate capacity of the NGH frames allocated to carry this logical channel

A constant cell capacity is allocated to each LC, which may be distributed in any way among the RF

channels, as long as continuous reception is possible with a single tuner Reception with a single tuner is enabled through a particular minimum distance in time of the relevant symbols on the different RF

channels This distance shall be equal or larger than 5 ms (rounded up to the nearest number of OFDM symbols) plus additional time for channel estimation to finalise and restart (additional 2(DY-1) symbols) where Dy is a parameter of the scattered pilot pattern in use

When the bit rates of the input streams are appropriately selected, the corresponding cell rate may

approach the logical channel capacity of the NGH frames, but normally not match it exactly The logical frames are defined to always exactly fill the data cell capacity of the corresponding NGH frames, but to adjust for the mismatch between required cell rate of input streams and available capacity auxiliary stream cells and/or dummy cells are added in the logical frame so that each logical frame of a particular logical channel gets the same size in cells during one logical super-frame

A set of NGH physical layer frames forms a super-frame Changes of physical layer parameters can only be done at super-frame boundaries A super-frame may contain FEFs at regular intervals (e.g after every Nthframe) A particular frame only carries cells from one logical channel In a super-frame there may be any allocation of logical channels to NGH frames, but this allocation may not change across super-frames, unless there is a reconfiguration, which in general is not seamless

4.3.3 Logical channel types

As can be seen from the above, the logical frames and the NGH frames can be seen as two different

protocol layers, which are largely independent The logical frames have their own L1 signaling (L1-POST) and are carried as the payload of the available capacity in the NGH frames The NGH frames also have their own signalling (L1-PRE) and offer a data cell capacity to the logical frames

Similar to other protocols, the  “packet  size”  of  the  higher  protocol  layer  does  not  need  to  perfectly  match  the capacity of the lower layer With LC type A there is a match in so far as each NGH frame carries exactly one logical frame This also applies to LC type D, albeit with multiple RF frequencies

However, with LC types B and C the logical frames are completely decoupled (unsynchronized) from the NGH frames With LC type B this is done using one RF channel and with LC Type C using multiple RF

channels LC type A can be seen as a special case of LC type B (both use a single RF channel, but with LC type A the logical frame is synchronized with the NGH frames) Similarly, LC type B can be seen as a special case of LC type C (both use logical frames that are unsynchronized with the NGH frames, but with LC type C the NGH frames may use different RF frequencies) In all cases reception is possible using a single tuner 4.3.4 Single tuner reception for frequency hopping

For LC type C, where there is no frequency hopping internally in an NGH frame, a sufficient requirement is that the time separation between NGH frames on different RF channels, carrying the same logical channel, fulfills the minimum tuning time requirement, as explained above

For LC type D the subslicing internally within one NGH frame is specified to ensure that this tuning time condition is fulfilled However, since a PLP may end on one RF channel in one NGH frame and may continue early in the following NGH frame on another RF channel, there must be some means to ensure, for every PLP, that the receiver has enough time to jump between the two RF frequencies also in this case

One way of achieving this is to use of a FEF part between the NGH frames In the FEF part there may e.g a DVB-T2 signal, during which the NGH receiver may jump to the next frequency without losing the service

Another way is to ensure that one or more other PLP types are used (for other services) between the

occurrences of the current PLP type One application is when the desired service is carried on a type 2 PLPs one may e.g use a sufficient number of symbols with type 1 PLPs in the beginning of the logical frame/NGH frame (these two are synchronized for LC type D) to allow time for frequency hopping When a service is carried on several PLPs these are co-scheduled in the NGH frame so that it makes no difference for the receiver from the frequency hopping point of view

P1 & AP1 symbol Insertion

D/A conversion

TX1 TX2 (optional)

eSFN predistortion

To transmitter(s)

Figure 9: OFDM generation

The input to the OFDM generation part is a sequence of QAM cells grouped in OFDM symbols each of which is comprised of a fixed number of QAM cells The pilot and reserved tone insertion block inserts scattered, continuous, and edge pilot cells as well as leaves space amongst the QAM cells for later insertion

of PAPR reduction tones by the PAPR reduction block if necessary P2 pilots are also inserted for P2 OFDM symbols The eSFN block pre-distorts the cells of each OFDM symbol to impose some time diversity at the receiver The IFFT transforms the sequence of QAM cells of each OFDM symbol into the time domain via an inverse Fourier transform The output of the IFFT is a time domain OFDM symbol whose crest factor may be reduced by the PAPR reduction PAPR reduction can use one or both of tone reservation and/or active constellation extension The guard interval insertion adds a cyclic prefix of the current time domain OFDM symbol to the beginning of the OFDM symbol A number of these cyclically extended symbols form an NGH frame which is delimited by the insertion of a first preamble (P1) symbol which in the MIMO, the hybrid and the hybrid MIMO profiles is followed by an additional first preamble (aP1) symbol The P1 (and aP1) symbols are special non-OFDM symbols which are modulated with information that describes how the following second preamble (P2) symbol is composed The last block in OFDM generation is the conversion

of the stream of time discrete signal samples into an analogue signal ready for up conversion into the RF transmit frequency and amplification

NOTE: The term "modulator" is used throughout the present document to refer to equipment

carrying out the complete modulation process starting from input streams and finishing with the signal ready to be upconverted and transmitted, and including the input interface,

formation of BBFRAMES, etc (i.e mode adaptation) However other documents may

sometimes refer to the mode adaptation being carried out within a T2-gateway, and in this context the term "modulator" refers to equipment accepting BBFRAMES at its input, and applying processing from the stream adaptation module onwards

Care should be taken to ensure these two usages are not confused

5 Input processing

5.1 Mode adaptation

The input to the NGH system shall consist of one or more logical data streams One logical data stream is carried by one Physical Layer Pipe (PLP) The mode adaptation modules, which operate separately on the contents of each PLP, slice the input data stream into data fields which, after stream adaptation, will form baseband frames (BBFs) The mode adaptation module comprises the input interface, followed by two sub-systems (the input stream synchronizer and the null packet deletion (the latter is optional for TSs)) and then finishes by slicing the incoming data stream into data fields and appending the baseband frame header (BBF-HDR) in front of each data field Each of these sub-systems is described in the following clauses

Each input PLP may have one of the formats specified in clause 5.1.1 The mode adaptation module can process input data for a PLP in one of three modes, the ISSY-IBS mode (one ISSY field per Logical Frame (LF) carried as part of the mandatory in-band signalling type B), the ISSY-BBF mode (one ISSY field per baseband frame carried in the baseband frame header) or the ISSY-UP mode (one ISSY field attached to each user packet), which are described in clause 5.1.7 The PLP mode – ISSY-IBS, ISSY-BBF or ISSY-UP - is indicated with the L1-POST configurable parameter PLP_ISSY_MODE (see clause 8.1.3.1)

Each TS input stream may be carried by a PLP cluster, i.e a maximum of four PLPs, including any common PLP Each GS input stream is carried by only one PLP (data PLP or common PLP) and each PLP may carry only one input GS A PLP cluster, that is carrying GS input streams associated with the same stream group

id, see L1 signalling, may carry a maximum of four GS input streams

The bit rates of any TS or GS input streams shall be such that the sum of the coded bit rates (after BCH and LDPC encoding) of a PLP cluster, i.e the PLPs carrying a particular TS, or a particular group of GS input streams, does not exceed 12 Mbit/s

5.1.1 Input formats

The input pre-processor/service splitter shall supply to the mode adaptation module(s) a single or multiple streams (one for each mode adaptation module) In the case of a TS, the packet rate will be a constant value, although only a proportion of the packets may correspond to service data and the remainder may be null packets

Each input stream (PLP) of the NGH system shall be associated with a modulation, a FEC protection mode and a particular time interleaving depth All three parameters are statically configurable and are indicated with the L1-POST configurable parameters PLP_MOD/PLP_ROTATION, PLP_COD and

ngh_stream_id allows the receiver to identify the correct TS for the reassembly operation in the receiver

If Null Packet Deletion is used, a DNP field is attached (1 byte) to each user packet The application

of Null Packet Deletion is indicated by the L1-POST configurable parameter PLP_NPDI, see clause 7.2

When only a single service (sub-)component is transported with a (partial) TS by the related PLP, TS header compression can be used leading to a 2 bytes shorter user packet length TS packet header compression is described in clause 5.1.1.1 below The different combinations of

attributes are explained in detail in clause 5.1.7, which distinguishes between the ISSY-LF mode, the ISSY-BBF mode and the ISSY-UP mode

 Generic Stream Encapsulation (GSE) [3]:

A GSE is characterised by variable or constant length packets, as signalled by the GSE packet headers

 Generic Continuous Stream (GCS) [?]:

A GCS is characterised by a continuous bit-stream or a variable length packet stream where the modulator is not aware of the packet boundaries

The L1-POST configurable parameter PLP_PAYLOAD_TYPE indicates, if the related PLP carries either a GCS, GSE, TS or a TS with header compression The L1-PRE parameter TYPE provides an overview over the stream types carried within the NGH super-frame it belongs to

5.1.1.1 Transport Stream packet header compression

TS packet header compression can optionally be applied to Transport Streams or partial Transport Streams,

if  they  carry  content  belonging  to  one  single  PID,  i.e  for  one  service  component  (video,  audio,  …) or service sub-component (SVC base layer, SVC enhancement layer, MVC base view or MVC dependent view) Null packets (PID 8191D) can still be part of that (partial) TS, i.e a distinction between the service (sub-

)component PID and the null packet PID is enabled

Also under the aforementioned circumstances TS packet header compression is an optional feature and its use is up to the provider The compression and decompression process is fully transparent

The signal flow consists of a direct path where TS packet header compression is applied and a path where it

is not applied The feature is applicable to an entire Physical Layer Pipe (PLP), i.e a PLP carrying a (partial)

TS can use one of the two paths sketched below, if the aforementioned conditions are fulfilled The use of

TS packet header compression is signalled with L1-POST configurable parameter PLP_PAYLOAD_TYPE

TS packet header compressor

L1-POST configurable signalling for TS or TS packet header compression Transport Stream packets

Transport Stream packets with compressed headers

Full PID and TP flag inserted

in baseband frame header Transport Stream packets

Figure 10: TS packet header compression on transmitter side

TS packet header decompressor

L1-POST configurable signalling for TS or TS packet header compression

Transport Stream packets

Transport Stream packets with compressed headers

Full PID and TP flag derived from baseband frame header Transport Stream packets

Figure 11: TS packet header decompression on receiver side

The packet header compression is defined as outlined below

Continuity counter

PID

Transport priority

Transport error indicator

Payload unit start indicator

Adaptation field control

R ep

la ce d

Not transmitted here, but in BBF-HDR

NULL packet indicator

Figure 12: Relationship between original and compressed TS packet headers (without sync byte)

The following parameters of the original TS packet header are compressed for transmission and

decompressed on receiver side (if needed) as follows:

Transport priority (TP): Not transmitted as part of the compressed TS packet header, but as part of the

baseband frame header PID: Replaced for compressed TS packet header by a single bit null packet indicator that

distinguishes between useful packets and null packets, the full 13 bit PID is Original TS packet header Compressed TS packet header

transmitted as part of the extended baseband frame header and can be re-inserted

by the TS packet header decompressor on receiver side Continuity counter: Reduced from 4 to 1 bit (continuity counter sync flag), provides synchronisation of

the receiver side 4-bit counter by the following conversion rule:

Continuity counter sync flag Continuity counter

1 0000

0 0001 to 1111 The original 4-bit count can be reconstructed on the receiver side for the error-free cases

5.1.2 Input interface

The input interface subsystem shall map the input into internal logical-bit format The first received bit will

be indicated as the most significant bit (msb) Input interfacing is applied separately for each single physical layer pipe (PLP), see figure 4

The Input Interface shall read a data field, composed of DFL bytes (Data Field Length), where:

 0 < DFL*8 < (Kbch - 64) for TS packet header compression, ISSY-BBF mode

 0 < DFL*8 < (Kbch - 48) for TS, GCS, GSE, ISSY-BBF mode

 0 < DFL*8 < (Kbch – 40) for TS packet header compression, ISSY-LF or ISSY-UP mode

 0 < DFL*8 < (Kbch – 24) for TS, GCS, GSE, ISSY-IBS or ISSY-UP mode

where Kbch is the number of bits protected by the BCH and LDPC codes (see clause 6.1)

The maximum value of DFL depends on the chosen LDPC code, carrying a protected payload of Kbch bits The 3-, 5-, 6- or 8-byte BBF-HDR is appended to the front of the data field, and is also protected by the BCH and LDPC codes

The input interface shall either allocate a number of input bits equal to the available data field capacity, thus breaking UPs in subsequent data fields (this operation being called "fragmentation"), or shall allocate

an integer number of UPs within the data field (no fragmentation) The available data field capacity is equal

to the maximum values being listed with the bullet points above for the different ISSY modes and input

formats, i.e Kbch-64, Kbch-48, Kbch-40 or Kbch-24, when in-band signalling is not used (see clause 5.2.3), but less when in-band signalling is used When the value of DFL*8 is smaller than the aforementioned

maximum values, a padding field shall be inserted by the stream adapter (see clause 5.2) to complete the LDPC/BCH code block capacity A padding field shall also be allocated in the first BBF of an interleaving frame, to transmit in-band signalling (whether fragmentation is used or not), if this is used See clause 5.2.3 for the different types of in-band signalling

5.1.3 Input stream synchronization (optional)

Data processing in the DVB-NGH modulator may produce variable transmission delay on the user

information The Input Stream Synchronizer subsystem shall provide suitable means to guarantee Constant Bit Rate (CBR) and constant end-to-end transmission delay for any input data format The use of the Input Stream Synchronizer subsystem is optional for PLPs carrying GSE or GCS streams In the case of PLPs

carrying transport streams (TS), it shall always be used

Input stream synchronization shall follow the specification given in annex C.1 This process will also allow synchronization of multiple input streams travelling in independent PLPs, since the reference clock and the counter of the input stream synchronizers shall be the same

The ISSY field (Input Stream Synchronization, 3 bytes) carries the value of a counter clocked at the

modulator clock rate 1/T (where T is defined in clause 11.4) and can be used by the receiver to regenerate

the correct timing of the regenerated output stream The ISSY field carriage shall depend on the input stream format and on the PLP mode, as defined in clauses ??? and figures 18 to 19 In ISSY-UP mode the ISSY field is appended to UPs for packetized streams In ISSY-IBS mode a single ISSY field is transmitted per interleaving frame in the in-band signalling type B, taking advantage of the fact that UPs of an interleaving frame experience similar delay/jitter

When the ISSY mechanism is not being used, the corresponding fields of the in-band signalling type B, if any, shall be set to '0'

A full description of the format of the ISSY field is given in annex C.1

5.1.4 Compensating delay

The interleaving parameters PI and NTI (see clause 6.6), and the frame interval IJUMP (see clause 6.6) may be

different for the data PLPs in a group and the corresponding common PLP In order to allow the

re-assembly of a service from the PLPs in its PLP cluster (for Transport Streams, the recombining mechanism described in annex A is used) without requiring additional memory in the receiver, the input streams (PLPs) shall be delayed in the modulator following the insertion of Input Stream Synchronization Information The delay (and the indicated value of TTO - see annex C.1) shall be such that, for a receiver implementing the buffer strategy defined in clause C.1.1, the partial transport streams at the output of the de-jitter buffers for the data and common PLPs would be essentially co-timed, i.e packets with corresponding ISCR values

on the two streams shall be output within 1 ms of one another

The compensating delay shall also be used, when the input stream is additionally transmitted from a second modulator with different PLP parameters (e.g., time interleaver duration), and if it is intended for a receiver to hand over from one signal to the other or to combine both received signals

5.1.5 Null Packet Deletion (optional, for TS only, ISSY-IBS, ISSY-BBF and

ISSY-UP modes)

Transport Stream rules require that bit rates at the output of the transmitter's multiplexer and at the input

of the receiver's demultiplexer are constant in time and the end-to-end delay is also constant For some Transport Stream input signals, a large percentage of null packets may be present in order to accommodate variable bit rate services in a constant bit rate TS In this case, in order to avoid unnecessary transmission overhead, TS null packets shall be identified (PID = 8191D) and removed The process is carried out in a way that the removed null packets can be re-inserted in the receiver in the exact place where they were

originally, thus guaranteeing constant bit-rate and avoiding the need for time-stamp (PCR) updating When Null Packet Deletion is used, useful packets  (i.e  TS  packets  with  PID  ≠  8  191D), including the

optionally appended ISSY field (ISSY-UP mode), shall be transmitted while null packets (i.e TS packets with PID = 8 191 ), including the optionally appended ISSY field, may be removed, see figure 13

After transmission of a UP, a counter called DNP (deleted null packets, 1 byte) shall be first reset and then incremented at each deleted null packet When DNP reaches the maximum allowed value DNP = 255D, then

if the following packet is again a null packet this null packet is kept as a useful packet and transmitted

Insertion of the DNP field (1 byte) shall be after each transmitted UP according to clause 5.1.7 and

C

I S

Y

Null packet deletion

Null packets

Useful packets

DNP counter

DNP (1 byte) insertion after next useful packet

Reset after DNP insertion

C

I S

Y

UP

S N

C

I S

Y

UP

S N

C

I S

Y

UP

S N

C

I S

Y

UP

S N

C

I S

Y Figure 13: Null packet deletion scheme

5.1.6 Baseband frame header (BBFHDR) insertion

A BBFHDR of a fixed length of either 8 (TS packet header compression applied in ISSY-BBF mode), 6 (all remaining input stream formats in ISSY-BBF mode), 5 (TS packet header compression applied in ISSY-IBS or ISSY-UP mode) or 3 bytes (all remaining input stream formats in ISSY-IBS or ISSY-UP mode) shall be inserted

in front of the baseband data field in order to describe the format of the data field The BBFHDR shall take one of four forms as shown in figures 14 to 17:

 Input stream format TS packet  header  compression  (PLP_PAYLOAD_TYPE  ≠  “xxxxx”),  

ISSY-BBF mode (figure 14 below)

 Input stream format other than TS packet header compression (PLP_PAYLOAD_TYPEs), ISSY-BBF mode (figure 15 below)

 Input stream format TS packet header compression (PLP_PAYLOAD_TYPE = ), ISSY-LF or ISSY-UP mode (figure 16 below)

 Input stream format other than TS packet header compression (PLP_PAYLOAD_Types ), ISSY-LF or ISSY-UP mode (figure 17 below)